It has been known since 1888 that light causes artists pigments to fade, and different light sources vary in the manner in which they affect the rate of fading. In 1888, in an article by W. J. Russel and W. de W. Abney entitled "Action of light on water-colours" (Report to the Science and Art Department of the Committee of Council on Education, HMSO, London, 1888), the authors described a series of experiments they conducted on different light sources and the extent to which they caused fading of artists pigments.
Concern about this phenomenon intensified in the 1950's. Thus, for example, L. S. Harrison, in a "Report on the Deteriorating Effects of Modern Light Sources" (Metropolitan Museum of Art, New York, 1953) tabulated data from a National Bureau of Standards report and disclosed that damage tended to increase with decreasing wavelength.
In 1986, T. Kenjo, in an article entitled "Certain deterioration factors for works of art and simple devices to monitor them" (International Journal of Museum Management and Curatorship May, 1986, at pages 295-300) described studies he had conducted into the effects of radiation at seven wavelengths (from 390 nanometers to 700 nanometers) on six different colorants. However, although Kenjo further discussed the problem of this phenomenon, he did not suggest a satisfactory solution.
To the best of applicant's knowledge, no satisfactory solution has been developed for this problem. The most common solution used is to control the overall illumination and/or annual exposure of the artwork to a level appropriate for the most sensitive materials present therein; see, e.g., G. Thompson, "The Museum Environment," 2.sup.nd Edition (Butterworths, London, 1986), at pages 22-34. However, the illumination used for this "solution" does not provide an adequate light level and/or color balance for the proper viewing of the artwork.
Another common solution is to minimize the amount of ultra-violet radiation which is allowed to impact the artwork. Although this solution is partially effective, it does nothing to affect the damage done by visible part of the light spectrum
It is an object of this invention to provide a process for illuminating artwork which produces an aesthetically pleasing and accurate display of the artwork while simultaneously minimizing damage to the artwork from radiant energy.